1. Field of the Invention
The present invention relates to an apparatus and a method for controlling the shape of structures. More particularly, the invention relates to an apparatus and a method for controlling the shape of structures for adaptive wings, hydrodynamic lifting surfaces, submarine hulls and other structures.
2. The Prior Art
Adaptive wings with variable leading and trailing edge devices have been studied to enhance maneuvers, to reduce the critical root bending moment, to reduce drag and to improve gust-alleviating response. Unlike these studies, where shape changes are achieved by moving the leading and trailing edges, the invention enables the use of adaptive wings to improve aircraft performance during transonic cruise, a problem which requires smaller shape changes, but primarily in the region between the leading and trailing edges. The shock induced drag can be reduced dramatically during transonic cruise if the airfoil has the correct shape. Wings that are optimized for a single cruise condition, therefore, usually have high drag at other cruise conditions. However, by adaptively modifying the wing cross section, it is possible to maintain optimum performance as the flight condition changes. The required shape change has been found to be small and therefore achievable.
The principal object of the invention is to provide an apparatus and a method for controlling the shape of structures efficiently, effectively and reliably.
An object of the invention is to provide an apparatus and a method for controlling the shape of structures for adaptive wings with efficiency, effectiveness and reliability.
Another object of the invention is to provide a method for developing the actuator stroke matrix that is used as a gain matrix to compute the strokes and stroke-error correction commands of internal translational actuators to achieve the desired structural shape when actuator stroke control is used.
Still another object of the invention is to provide a method for developing the actuator-load matrix that is used as a gain matrix to compute the loads and load errors of internal translational actuators to achieve the desired structural shapes when actuator load control is used.
Yet another object of the invention is to provide a method which can be applied to structures with stiffness matrices that are singular with the actuators removed.